JPS6044508B2 - Piston reciprocating internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides the following advantages:
This invention relates to an improvement in a piston reciprocating internal combustion engine that converts reciprocating motion of a piston into rotational motion.

In the above-mentioned reciprocating piston internal combustion engine, a predetermined piston clearance is usually provided between the piston and the cylinder wall to cope with thermal expansion of the piston.

By the way, in the case of using a piston made of aluminum alloy, the thermal expansion is large, so the piston clearance needs to be correspondingly large. However, if the piston clearance is increased, when the piston changes direction during engine operation, the piston will tilt and hit the cylinder wall, producing so-called hitting side noise (piston slap) and causing uneven wear. Undesirable. Then there are the Pistons. For the purpose of reducing lapping, a method has been proposed in which a relatively thick oil film is formed by forcibly injecting lubricating oil into the piston clearance between the piston and the cylinder, thereby regulating the inclination of the piston with respect to the cylinder wall. However, in this case, for example, O,
If lubricating oil with a thickness of 1WUfL is attached, the engine [80wrm x 80wgn (bore diameter x stroke) / 3
000μm], a large amount of lubricating oil of approximately 2cri/O, Olsec, or approximately 200cTitlesec will be scraped off by the edge of the lower end of the piston during the downward stroke of the piston from top dead center to bottom dead center. Forcefully injecting a large amount of lubricating oil into the piston clearance requires extremely high oiling pressure and a passage with a large cross-sectional area, and is not equipped with a means for forcibly injecting lubricating oil such as a hydraulic pump. There was a problem that it could not be applied to internal combustion engines.

In order to solve these problems, the present invention can reduce the noise caused by piston slap without using forced lubricating means such as a hydraulic pump, and can also prevent uneven wear of pistons and cylinders to improve their durability. The present invention aims to provide a reciprocating piston internal combustion engine that can improve performance. In order to achieve this object, the internal combustion engine according to the present invention has an oil scraper link fitted around the circumference of the piston skirt, and adjacent to and shallower than the ring fitting groove above and below the ring fitting groove. Annular grooves are respectively formed, and the circumferential surface of the piston skirt portion between the lower annular groove and the lower end of the piston has approximately the same depth as the groove, and an upper end communicates with the groove. A plurality of oil guiding recesses are provided along the sliding direction of the piston, or a shallower annular groove is formed above the ring fitting groove adjacent to the ring fitting groove, and the oil scraping ring The entire circumference of the piston skirt section from the fitting groove to the lower end of the piston is formed into an oil guiding recess that is shallower than the fitting groove, so that the lower edge of the oil guiding recess especially during the downward stroke of the piston is used to guide the cylinder. A large amount of lubricating oil adhering to the wall is guided into the recess without being scraped off, and is scraped up by an oil scraping ring to create a high-pressure oil that is transferred into the annular groove below the ring. This is characterized in that a thick oil film is formed by ensuring sufficient oil or by directly supplying the oil to the piston clearance below the scraper ring, thereby reducing piston slap.

In addition, as a related prior art, a technique in which an oil scraping ring is fitted to the circumferential surface of the piston skirt is disclosed in Japanese Patent Application Laid-open No. 48.
-21014 and Japanese Utility Model Application Laid-open No. 53-78307, in which a recess is formed in the piston skirt, but in contrast to these, the present invention has the above-mentioned oil guiding recess formed in the piston skirt. Below the piston from the provided oil scraping ring! It is characterized by the fact that it is formed all the way to the end edge.

Hereinafter, the present invention will be specifically explained based on embodiments shown in the drawings.

1 to 3 show an example in which the present invention is applied to a diesel engine, in which reference numeral 1 is a cylinder block, 2 is a cylinder head 3 is a cylinder.

A piston 4 made of light aluminum alloy is fitted into the cylinder 3, and a combustion chamber 7 having intake and exhaust valves 5 and a fuel injection valve 6 is formed above the piston 4 of the cylinder 3. ing. The piston 4 is configured to reciprocate within the cylinder 3 while maintaining airtightness by fitting a piston ring 8 consisting of a gas ring 8a and an oil ring 8b to its top peripheral surface, and this reciprocating motion This is converted into a rotational motion of a crankshaft (not shown) via a connecting rod 9, and at this time, the lubricating oil stored in the crankcase 10 is splashed onto the inner wall of the cylinder 3) and the piston 4. , lubricates and cools the piston and cylinder. As shown in FIGS. 2 and 3, an oil scraper ring 11 is provided on the outer periphery of the substantially central portion of the skirt portion 4a of the piston 4, and is in sliding contact with the inner wall of the cylinder 3.
is fitted onto the fitting groove 12 for the ring 11,
Annular grooves 12a and 12b, which are shallower than the fitting groove 12, are formed adjacent to the fitting grooves 12a and 12b on the lower side. A large amount of lubricating oil is secured, and the lubricating oil is uniformly guided in the circumferential direction of the piston through the groove. In particular, on the circumferential surface of the piston skirt portion 4a between the annular groove portion 12b below the oil scraper ring 11 and the piston edge portion 4b at the lower end of the piston 4, there is a portion approximately equal to the groove portion 12b. A plurality of oil guiding recesses 13 having the same depth and communicating with the groove 12b at the upper end are bored along the sliding direction of the piston, and between the recess 13 and the wall surface of the cylinder 3. The piston edge portion 4 of the recess 13 is provided with a somewhat large gap during the piston's downward stroke.
In b, the lubricating oil adhering to the wall surface of the cylinder 3 is not scraped off.

Further, the groove portion 12 is formed on the thrust surface 4c of the piston skirt portion 4a above the oil scraper ring 11.
An oil diffusion groove 14 communicating with a is bored at a position substantially perpendicular to the piston pin and along the sliding direction of the piston 4.

With this configuration, the lubricating oil in the crankcase 10 is splashed onto the wall surface of the cylinder 3 due to engine operation, and when lubricating the piston and male cylinders 3, a large amount of lubricating oil is deposited in the piston clearance. can be ensured. That is, when the piston 4 rises and is at the top dead center, the lubricating oil attached to the inner wall of the cylinder 3 is transferred to the edge portion 4b of the oil guiding recess 13 that is spaced from the inner wall surface of the cylinder 3 during the downward stroke of the piston 4. The oil is guided into the recess 13 without being scraped off by the oil scraper ring 11 and is scraped into the guiding recess at an extremely high speed, and the pressure inside the crankcase increases at that time, resulting in a high pressure. The ring 11 moves into the annular groove 12b and is sufficiently secured therein.
is fed into the piston clearance below. As a result, a thick oil film is formed within the piston clearance, and this oil film restricts the inclination of the piston 4 when the direction of movement of the piston 4 is changed upward, which in turn reduces piston slap, and also reduces the piston 4 and the piston 4. This prevents uneven wear of the cylinder 3. Also, piston 4
When the lubricating oil rises, the lubricating oil on the inner wall of the cylinder 3 is scraped up at a high speed by the oil scraping ring 11, the pressure increases, and the oil is guided into the groove 12a and further into the oil diffusion groove 14. A relatively thick oil film is formed within the piston clearance, especially in the vicinity of the thrust surface 4c orthogonal to the piston pin, thereby regulating the inclination of the piston 4 when changing the direction of downward movement, reducing piston slap, and ultimately Uneven wear of the cylinder 3 can be prevented. In addition, in this example,
Although a plurality of oil guiding recesses 13 communicating with the grooves 12b are formed on the circumferential surface of the piston skirt portion 4a, they may be formed on the entire circumferential surface of the piston skirt portion 4a below the oil scraping ring 11. During the downward stroke of the piston 4, the lubricating oil adhering to the wall of the cylinder 3 guided into the oil guiding recess 13 is scraped into the guiding recess 13 at an extremely high speed by the oil scraping ring 11, and at that time. As the pressure within the crankcase increases, the pressure becomes high and is supplied to the piston clearance below the ring 11, that is, the recess 13, forming a thick oil film.

Thus, according to the present invention, a large amount of lubricating oil adhering to the cylinder wall surface is captured especially during the downward stroke of the piston, increasing its pressure, and this large amount of lubricating oil is secured within the piston clearance and becomes relatively thick. Since it forms a layer of oil film, it is possible to control the inclination of the piston when changing its direction of motion upward, reducing noise caused by piston slap, and also preventing uneven wear of the piston and cylinder, extending the service life of the engine. Therefore, the structure is simple since no forced lubricating oil injection means is required, and the present invention can be applied to reciprocating internal combustion engines that do not have such a means. can be obtained/received.

[Brief explanation of drawings]

FIG. 1 is a vertical view of the main parts of an internal combustion engine according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line I-1 in FIG. 1, and FIG. 3 is a cross-sectional view of the piston in FIG. 2. ■It is a sectional view along the line. 1...Cylinder block, 2...Cylinder head, 3...Cylinder, 4...Piston, 5...Suction and exhaust valves, 6...・Fuel injection valve,
7... Combustion chamber, 8... Piston ring, 8a... Gas ring, 8... Oil ring, 9... Conn rod, 10.・Crankcase, 11... Oil scraping ring, 12...
...Fitting groove, 12a, 12b...Groove, 13.
...Oil guiding recess, 14...Oil diffusion groove.

Claims (1)

[Claims] 1. In an internal combustion engine in which a piston is fitted into a cylinder and the reciprocating motion of the piston is converted into rotational movement, an oil scraping ring is fitted around the circumference of the skirt portion of the piston, and an oil scraping ring is fitted around the circumference of the skirt portion of the piston. A shallower annular groove is formed above and below the fitting groove adjacent to the fitting groove, and a groove is formed on the circumferential surface of the piston skirt portion between the lower annular groove and the lower end of the piston. A plurality of oil guiding recesses are provided along the sliding direction of the piston and have approximately the same depth and whose upper ends communicate with the groove, or above the ring fitting groove. A shallower annular groove is formed adjacent to the groove, and the entire circumferential surface of the piston skirt section from the oil scraping ring fitting groove to the lower end of the piston is formed into an oil guiding recess shallower than the fitting groove. A piston reciprocating internal combustion engine characterized by: